Some industrial systems require a liquid having a specific conductivity to be used, such as pure water. Therefore, it is important to monitor the conductivity of the liquid in such systems. In the past, some conductivity meters made measured conductivity over an extended range by dividing up the range into several decades and providing a separate conductivity cell for each decade. However, a conductivity meter that contains multiple conductivity cells is bulky and impractical for industrial applications. Further, the separate conductivity cells were only calibrated for one fixed frequency, usually the frequency located in the middle of the decade. However, because of non-linear effects, the measurements associated with values lying at the edges of each decade were not as accurate.
Accordingly, there is a need for a conductivity meter that accurately measures conductivity over a range of several decades, eliminates the need for multiple conductivity cells, and minimizes the non-linear effects detrimental to accuracy. The present invention satisfies this need.
Further, there is a need for a meter that can be calibrated to a standard (NIST) on the outskirt of the meter's conductivity range and maintain accuracy throughout the meter's entire conductivity range. The present invention satisfies this need.